import type { JsonObject } from '@xylabs/object';
import type { UserEvent } from './Api/index.ts';
import { PixelApi } from './Api/index.ts';
import type { ExIds } from './ExIds.ts';
/** Singleton pixel tracker that queues and sends user events to the XY Labs tracking API. */
export declare class XyPixel {
    static api: PixelApi;
    private static _instance?;
    private static utmFieldsObj;
    cid: string;
    email?: string;
    email_hash?: string | null;
    exids?: ExIds;
    pixelId?: string;
    queue: UserEvent[];
    private queueMutex;
    private constructor();
    /** Returns the singleton XyPixel instance, throwing if not yet initialized. */
    static get instance(): XyPixel;
    /**
     * Initializes the XyPixel singleton with the given pixel ID.
     * @param pixelId - The pixel identifier for this tracking instance
     * @returns The newly created XyPixel instance
     */
    static init(pixelId: string): XyPixel;
    /**
     * Replaces the default PixelApi instance used for sending events.
     * @param api - The PixelApi instance to use
     */
    static selectApi(api: PixelApi): void;
    private static utmFields;
    /**
     * Associates an email address with this pixel instance, hashing it for privacy.
     * @param email - The email address to identify the user with
     */
    identify(email?: string): void;
    /**
     * Queues a tracking event and attempts to flush the queue to the API.
     * @param event - The event name
     * @param fields - Optional event-specific fields
     * @param eventId - Optional unique event identifier
     */
    send<T extends JsonObject>(event: string, fields?: T, eventId?: string): Promise<void>;
    private tryFlushQueue;
    private updateFbId;
}
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